Abstract

SCHISTOSOMIASIS SNAIL-INTERMEDIATE HOST CONTROL, USING A NATURAL PLANT

*Daniel, U. N.¹, Onyemekara N. N.², Ohalete, C. N.³, Nnoli M. C.⁴

¹Department of Biological Science, Federal University of Technology, Owerri. Imo State, Nigeria.
²Department of Microbiology, Federal University of Technology, Owerri. Imo State, Nigeria.
³Department of Microbiology, Imo State University, Owerri, Imo State. Nigeria.
⁴Department of Biotechnology, Federal University of Technology, Owerri. Imo State, Nigeria.

ABSTRACT

Snails, intermediate vectors of Schistosomiasis were subjected to several treatments with different concentrations of leaf, bark, seed and mixed extracts of the plant Neem (Azadirachta indica) to determine molluscicidal tendencies of the plant. The study sampled one thousand five hundred and forty (1540) snails of the species Bulinus globosus obtained from Otamiri River in Ihiagwa, Owerri West Local Government Area of Imo State, South Eastern Nigeria. Twenty (20) snails were treated for each of the extract concentration- 25%, 50% and 100%, plus a triplicate of each of the concentrations. Two methods of extraction- decoction and methanol were employed and the different set of extracts tested to determine which method produced the most efficient extracts and the concentration that produced the highest snail mortality. These experiments were maintained at time schedules of 8h, 16h and 24h. Results obtained show that all the snails were susceptible (except those for the control) but differed on times taken to achieve maximum mortality. Moreso, extracts from methanol extraction method killed the snails faster than those got from decoction extraction method. At 25% concentration, the mixed extracts (by Methanol method), had the highest molluscicidal activity (45.4%) at the shortest time of exposure (ie 8hrs), while the bark extract had the least (0%) while leave and seed extracts had 18.2% and 36,4% mortality respectively. There was a significant difference in the mortality rates at this concentration level of the different extracts (P < 0.05 = 10.660). Also at 100% concentration, the mixed extracts (by Methanol method), had the highest molluscicidal (36.4%) at the shortest time of exposure (ie 8hrs), while the least molluscicidal activity was achieved with the bark extract (15.1%) at same period of exposure, while the leave and seed extracts yielded 21.2% and 27.3% respectively, and there was a significant difference in the mortality rates at this concentration level of the different extracts (P < 0.05 = 10.444). Furthermore, in comparing the two methods of extraction, at 25% extract concentration and at least time of exposure (8hr), the mixed extracts from Methanol extraction method yielded 55.5% snail mortality, while the mixed extracts from Decoction extraction method yielded 44.5% snail mortality. Also, at 100% extract concentration and at least time of exposure (8hr), the mixed extracts from Methanol extraction method yielded 57.1% snail mortality, while the mixed extracts from Decoction extraction method yielded 42.9% snail mortality. Similarly, results of the study carried out to determine the phytochemical properties of the extracts revealed that out of the six properties tested for, only alkaloid was absent in bark and leave extracts, while the three extracts had all the other components. This method of snail control is cheap and easy to practice and could be adopted to halt further development and transmission of the schistosome to the definitive host, hence contributing to schistosomiasis eradication in the tropics.

Keywords: Snails, Azadirachta indica, Molluscicidal, Neem, Owerri, Nigeria.